Effects of Azidosilane Treatments of Wood and Cellulose Fiber Surfaces on Adhesion to Polypropylene

Abstract

Wood strip surfaces (Aspen and Birch) and cellulose fibers (Birch, pulped paper fibers) were treated with azidosilane coupling agent, via immersion in methylene chloride and methanol solutions respectively, and then subsequently dried.Polypropylene films were compression molded to the wood surfaces and peel forces were measured.The treated cellulose fibers were suspended and mixed with polypropylene fibers in water, formed into thin sheets by wet forming, dried, and compression molded to melt the polypropylene.Treated wood surfaces gave two to six times the dry peel force versus untreated wood surfaces.However, the wet peel force of treated wood degraded to that of untreated wood.The elongation, fail stress, and tensile energy absorption of treated molded sheets were all increased over the untreated fibers for both dry and wet testing; the wet-tested properties were especially enhanced by the silane treatment.

Effect of chemical modification of wood on the mechanical and adhesion properties of wood fiber/polypropylene fiber and polypropylene/veneer composites

“…Since mechanical properties of the composites are related to the compatibility and interaction between the components, improvement of the interface and interphase interactions in polypropylene/wood composites is essential. Approaches to improve the interaction and thereby the stress transfer between lignocellulosics and polypropylene include, for instance, the use of coupling agents and compatibilizers of various kinds (Kolosick et al 1990, Oksman and Clemons 1997, Westerlind and Berg 1988. Coating of wood ®ller with thermoset resin has also been proved to enhance the mechanical properties of wood/polypropylene composites (Sain and Kokta 1993).…”